1. Field of the Invention
The present invention relates to a machine for affixing, by means of an ink jet printing device, a postage mark to a flat object such as an envelope or a label, and relates more precisely to a machine of this type with manual insertion.
2. Description of the Prior Art
In an automatic mail processing machine, envelopes are generally carried through the machine by a carrying device such as a conveyor belt, along a path that runs from an entry point to an exit point, passing through the printing station. This is not the case in an office machine with manual insertion, into which the user partially inserts the envelope through an insertion opening of the machine; the envelope receives the postage mark, after which the user manually withdraws the envelope.
There is a known machine for metering a flat object such as an envelope or a label, marketed under the name Personal Post Office by the Pitney Bowes company, of the following type: the machine comprises, in a frame, an opening for the manual insertion of an object leading to two stops at right angles, a device for holding an object by gripping it between a fixed upper ceiling comprising a window and a lower plate vertically movable by means of a drive mechanism, an ink jet printing device whose nozzles are disposed inside the window of said ceiling, and a sensor of the presence of an object in the vicinity of the corner of the stops, which starts the drive mechanism of the plate for gripping the object and the print cycle. The printing is done in a single pass of the print head (in a reference direction that will be described as longitudinal); in order to allow this single pass, the head is specific and has non-standard dimensions that allow it to transversely cover the entire area to be metered in one movement. However, the need for a special print head increases the cost of the machine.
In order to be able to use standard print heads, which generally cover ⅙ of an inch (4.23 mm) transversely, it is conceivable to use several heads disposed and coordinated so as to cover the entire metering area in one pass, or to make a print head movable in the transverse direction, i.e., perpendicular to the direction of the printing pass, in order to have it complete several staggered passes covering the printing area. Both of these solutions substantially complicate the production of the machine and add to its price.
The object of the invention is to eliminate these drawbacks and to offer a simple and compact machine that accommodates standard print heads.
This object is achieved according to the invention by a postage metering machine of the above-mentioned type, equipped with a device for transversely moving the object in front of the printing device, even while the object is gripped.
This transverse moving device, which has only a small range of travel to complete, is advantageously a horizontally movable rake whose teeth pass one of said stops (the longitudinal one) in order to transversely push the edge of a detected object.
The rake is advantageously driven by a motor, preferably through a screw-nut system.
This motor is preferably independent from the one with which the printer is equipped for the longitudinal movements of the print head. On the other hand, the vertical movement of the plate is advantageously executed in one direction by means of the same engine that drives the rake and in the opposite direction by means of antagonistic springs. Preferably, the springs act in the direction of the gripping of the object, and their force is calculated to be able to grip the document lightly without counteracting the transverse movement imparted by the rake.
Also advantageously, the movement of the plate is executed by means of the movement of the rake. For this reason, the plate and the rake are preferably linked by at least one flexible tie.
The machine of the invention operates in the following way. Initially, the plate being in the retracted position, the user inserts the object to be metered into the insertion opening as far as its stops, so that the top right corner of the object is detected by the sensor, which starts the next cycle. The motor of the rake turns on and drives both the forward movement of the rake, whose teeth are still behind the longitudinal stop, and the lifting of the plate by the springs, until the object is gripped, then pressed against the reference ceiling. The plate comes to a stop while the rake continues to move forward and pushes the object with its teeth, which pass the longitudinal stop, in order to first correct the object""s position if necessary, then, in successive steps coordinated with the printing passes, to have it receive the postage mark. Once the printing is finished, the motor of the rake runs in the opposite direction so that the rake is drawn backward and drives the descent of the plate, thereby releasing the envelope, which can be removed by the user.
The machine of the invention therefore allows non-contact ink jet printing onto media of variable thicknesses and dimensions, with the following guarantees:
the top side of the flat object is always kept at a constant distance from the ejection nozzles during printing,
the holding device makes it possible to process objects having variable thicknesses,
the moving device makes it possible to process objects of variable dimensions, the same machine processing both small labels or envelopes as well as large envelopes,
the moving device does not cause any folding of the outer surfaces of the objects during the movement so as not to diminish the print quality, thanks to a recess in the ceiling facing the window provided in the plate,
the device makes it possible to print a postage mark in a precise area of the article processed.